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`timescale 1ns / 1ps

// ============================================================================

//        __

//   \\__/ o\    (C) 2007-2018  Robert Finch, Waterloo

//    \  __ /    All rights reserved.

//     \/_//     robfinch<remove>@finitron.ca

//       ||

//

//      fpZLUnit.v

//              - zero latency floating point unit

//              - instructions can execute in a single cycle without

//                a clock

//              - parameterized width

//              - IEEE 754 representation

//

//

// This source file is free software: you can redistribute it and/or modify 

// it under the terms of the GNU Lesser General Public License as published 

// by the Free Software Foundation, either version 3 of the License, or     

// (at your option) any later version.                                      

//                                                                          

// This source file is distributed in the hope that it will be useful,      

// but WITHOUT ANY WARRANTY; without even the implied warranty of           

// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the            

// GNU General Public License for more details.                             

//                                                                          

// You should have received a copy of the GNU General Public License        

// along with this program.  If not, see <http://www.gnu.org/licenses/>.    

//                                                                          

//      fabs    - get absolute value of number

//      fnabs   - get negative absolute value of number

//      fneg    - negate number

//      fmov    - copy input to output

//      fsign   - get sign of number (set number to +1,0, or -1)

//      fman    - get mantissa (set exponent to zero)

//  fcmp

//

// ============================================================================

`define VECTOR  6'h01

`define VFABS   6'h03

`define VFSxx   6'h06

`define VFSxxS  6'h07

`define VFNEG   6'h16

`define VSEQ        3'd0

`define VSNE        3'd1

`define VSLT        3'd2

`define VSGE        3'd3

`define VSLE        3'd4

`define VSGT        3'd5

`define VSUN        3'd7

`define VFSIGN  6'h26

`define FLOAT   6'h0F

`define FCMP    6'h06

`define FMOV    6'h10

`define FNEG    6'h14

`define FABS    6'h15

`define FSIGN   6'h16

`define FMAN    6'h17

`define FNABS   6'h18

`define FCVTSD  6'h19

`define FCVTSQ  6'h1B

`define FCVTDS  6'h29

module fpZLUnit

#(parameter WID=32)

(

    input [31:0] ir,

        input [WID-1:0] a,

        input [WID-1:0] b,       // for fcmp

        output reg [WID-1:0] o,

        output nanx

);

localparam MSB = WID-1;

localparam EMSB = WID==128 ? 14 :

                  WID==96 ? 14 :

                  WID==80 ? 14 :

                  WID==64 ? 10 :

                                  WID==52 ? 10 :

                                  WID==48 ? 11 :

                                  WID==44 ? 10 :

                                  WID==42 ? 10 :

                                  WID==40 ?  9 :

                                  WID==32 ?  7 :

                                  WID==24 ?  6 : 4;

localparam FMSB = WID==128 ? 111 :

                  WID==96 ? 79 :

                  WID==80 ? 63 :

                  WID==64 ? 51 :

                                  WID==52 ? 39 :

                                  WID==48 ? 34 :

                                  WID==44 ? 31 :

                                  WID==42 ? 29 :

                                  WID==40 ? 28 :

                                  WID==32 ? 22 :

                                  WID==24 ? 15 : 9;

wire [5:0] op = ir[5:0];

wire [1:0] prec = ir[25:24];

wire [5:0] fn = ir[31:26];

wire [2:0] sxx = {ir[25],ir[20:19]};

wire [4:0] cmp_o;

fp_cmp_unit #(WID) u1 (.a(a), .b(b), .o(cmp_o), .nanx(nanx) );

wire [127:0] sq_o;

//fcvtsq u2 (a[31:0], sq_o);

wire [63:0] sdo;

fs2d u3 (a[31:0], sdo);

wire [31:0] dso;

fd2s u4 (a, dso);

always @*

    case(op)

    `FLOAT:

        case(fn)

        `FABS:   o <= {1'b0,a[WID-2:0]};        // fabs

        `FNABS:  o <= {1'b1,a[WID-2:0]};        // fnabs

        `FNEG:   o <= {~a[WID-1],a[WID-2:0]};   // fneg

        `FMOV:   o <= a;                        // fmov

        `FSIGN:  o <= (a[WID-2:0]==0) ? 0 : {a[WID-1],1'b0,{EMSB{1'b1}},{FMSB+1{1'b0}}};    // fsign

        `FMAN:   o <= {a[WID-1],1'b0,{EMSB{1'b1}},a[FMSB:0]};    // fman

        //`FCVTSQ:    o <= sq_o;

        `FCVTSD: o <= sdo;

        `FCVTDS: o <= {{32{dso[31]}},dso};

        `FCMP:   o <= cmp_o;

        default: o <= 0;

        endcase

    `VECTOR:

        case(fn)

        `VFABS:  o <= {1'b0,a[WID-2:0]};        // fabs

        `VFSIGN: o <= (a[WID-2:0]==0) ? 0 : {a[WID-1],1'b0,{EMSB{1'b1}},{FMSB+1{1'b0}}};    // fsign

        `VFNEG:  o <= {~a[WID-1],a[WID-2:0]};   // fneg

        `VFSxx,`VFSxxS:

            case(sxx)

            `VSEQ:  o <=  cmp_o[0];

            `VSNE:  o <= ~cmp_o[0];

            `VSLT:  o <=  cmp_o[1];

            `VSGE:  o <= ~cmp_o[1];

            `VSLE:  o <=  cmp_o[2];

            `VSGT:  o <= ~cmp_o[2];

            `VSUN:  o <=  cmp_o[4];

            default:    o <= cmp_o[2];

            endcase

        default:    o <= 0;

        endcase

        default:        o <= 0;

        endcase

endmodule